php, 103 bytes

Result

AC

Duration

939ms

Code [DL]

<?php
$b=0;for($d=1;$c=fread(STDIN,1);$d=($d+1)%51){$d*=$c!='T';$b=$c=='K'||$b&&$d;echo!$d||$b?'A':$c;}

stdin

                                 T                
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
      K                                           

stdout

                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
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                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
                                 A                
      AAAAAAAAAAAAAAAAAAAAAAAAAAAA                

stderr

strace